Device for detecting the end of a roll of copy paper in a photocopying machine or the like

ABSTRACT

A photocopy paper feed device control circuit contains a phototransducer which measures the intensity of light reflected from the surface of a roll of stored photocopy paper and thereby detects the trailing end of a strip of paper coiled on the storage roll. Said control circuit actuates a photocopy paper feed device only when a predetermined amount of paper remains to be fed. The distance between the measuring point of the phototransducer element and a paper cutting device is greater then that between two pairs of feed rollers disposed in a section following said cutting device so that the feeding of undersized pieces of photocopy paper is prevented.

United States Patent 15 3,682,543 Iwamoto [451 Aug. 8, 1972 DEVICE FORDETECTING THE END [56] References Cited OF A ROLL OF COPY PAPER IN AUNITED STATES PATENTS 3 OCOPYING MACIHNE OR THE 3,425,777 2/1969 White..355/28 3,105,425 10/1963 Cerasani et a1. ..83/365 X [72] Inventor:Minoru Iwamoto, T k Japan 3,415,149 12/1968 Ziljberman et a1 ..83/365 X[73] Assignee: Kabushiki Kaisha Ricoh, Tokyo, Primary Examiner james MMeister Japan Attorney-Burgess, Ryan and Hicks [22] Filed: Jan. 21, 197057 ABS CT [21] Appl. No.: 4,489 1 A photocopy paper feed device controlcircuit contains a phototransducer which measures the intensity 1Forelgll pp y Data of light reflected from the surface of a roll ofstored Jan. 25, 1969 Japan ..44/5465 Paper and thereby detects the"ailing end of a strip of paper coiled on the storage roll. Said con-521 US. Cl. ..355/13 83/203 83/210 circuit mates Paper feed device83/36; 83/365 83/649 only when a predetermined amount of paper remains 5int Cl 15/00 to be fed. The distance between the measuring point [58]mid a m:1::jjjjjjjjijjiiijii zalm 8% 156 of the phomansducer element anda Paper cutting device is greater then that between two pairs of feedrollers disposed in a section following said cutting device so that thefeeding of undersized pieces of photocopy paper is prevented.

3 Claims, 2 Drawing Figures E a 1 i 1 E 4: DEVELOPING I DEVICE sub 43 2..sxmsuasl U; l O: l I 7 1 8c e 2 i 1 I 3 15.1 L'. l L 23- 80 F1 8c 8bDEVICE FOR DETECTING THE END OF A ROLL OF COPY PAPER IN A PHOTOCOPYINGMACHINE OR THE LIKE BACKGROUND OF THE INVENTION The present inventionrelates to a photocopy paper detecting device for use in copyingmachines or the like and, more particularly, to a device for measuringwhether a predetermined length of copy paper remains in the machine.

The invention is usable in a copying machine of the type which utilizesa long roll of photocopying paper which is fed by a paper feed device(such as a pair of feed rollers) into a cutting device, where it is cutto a predetermined length and then fed into an exposure device. Thephotocopying paper, having been exposed, is then fed between two spacedapart pairs of feed rollers in a developing section. If a piece ofphotocopy paper having a length insufficient to bridge the gap betweenthe two pairs of feed rollers is fed into the developing section in sucha copying machine, the paper will be fed into the developing section bythe first pair of rollers but will not be removed therefrom by thesecond pair. Instead it will jam in the copying machine developingsection requiring the disassembly of the developing device in order toremove it. Such disassembly work may be complicated and cumbersomeespecially where the developing device is complicated in constructionand contains a developing solution by which an operator may becontaminated. The under sized piece of copying paper mentioned abovemost often results when the end of a roll of copy paper is reached. Inaddition to the problem of jamming, the end of a roll of copy paperpresents a further problem as the paper quality there is generally notsuited for the copying operation, so that it is advantageous not to feedthe paper at the end of a roll into the developing section.

In conventional copying machines of the type described, judgment of theoperator is relied upon to prevent feeding of the trailing end of theroll of copy paper through the machine. If he does not stop the paperfeed on time, the jamming mentioned above occurs. On the other hand, inorder to avoid such jamming, the operator may replace the roll ofphotocopy paper before all the useable paper thereon is consumed, thuswasting photocopy paper.

Accordingly, one of the objects of the present invention is to provide aphotocopy paper detecting device which automatically permits the use ofa roll of photocopy paper until its last usable portion has beenconsumed, and then automatically rejects the unusable portion near thetrailing end of the roll. The present invention thereby facilitates thecopying operation, permits the maximum use of the usable photocopy paperon the roll, and prevents jamming of the tail end of the roll in thecopying machine. More particularly, the object of the present inventionis to provide a device for detecting whether a predetermined sufficientlength of photocopy paper remains in storage or not.

SUMMARY OF THE INVENTION In accordance with the present invention, thephotocopy paper leaving a storage roll is measured in order to determinewhether a predetermined length thereof remains or not. Measurement isaccomplished by a detection circuit in which a light source directslight upon the surface of the paper on the storage roll on which it isreflected into a phototransducer element. The intensity of the reflectedlight when paper is present on the roll is higher than when the roll isempty because the paper is more reflective than the empty roll. Therelatively high intensity of the reflected light from the paper on theroll may increase the electromotive force of a phototransducer on whichthe light falls or may lower the resistance of a suitable transducerelement so illuminated. Pending upon the intensity of the light someasured (and therefore upon the presence or absence of paper on thestorage roll) a paper feed device control circuit is closed as to feedthe paper or open so as to prevent the feed of the paper. Upon eachadvance of paper into the machine a predetermined length is cut off.When the leading edge of the cut paper reaches a normally-closed switch,said switch is opened thereby and, in turn, a power supply circuit forthe control circuit is opened so that said control circuit is reset forthe next paper feed operation.

In the device of the present invention, the distance from the point onthe roll where the phototransducer measurement is made to a photocopypaper cutting station is greater than the distance between two spacedapart pairs of feed rollers disposed in a section, for example adeveloping section, which follows the cutting device of the copyingmachine.

According to one embodiment of the present invention, a normally-closedswitch is situated in a light source circuit adapted to illuminate thephotocopying paper, and when the photocopying paper has been found ofsufficient length by the phototransducer element and the photocopyingfeed device control circuit, the normally-closed switch is opened sothat the light source for illuminating the photocopying paper is turnedoff.

According to a further aspect of the present invention, anormally-closed switch which is adapted to be temporarily opened insynchronism with the advancement of the photocopying paper feed deviceis also utilized as a normally-closed switch which is adapted to resetthe paper feed device control circuit whenever the feed of the paper isaccomplished.

According to the present invention, the remaining photocopying paper isautomatically, rapidly and positively measured whenever the feed of thepaper is accomplished so that the copying operation efficiency may beremarkably improved without wasting the photocopying paper or causingthe jamming of the paper in the copying machine. The detecting device ofthe present invention is simple in construction and has no mechanicalelements which contact the photocopying paper (which paper is notrequired to be specially prepared for use with the present invention),so that longer service life may be ensured. The light source forilluminating the photocopying paper is turned off whenever the feed ofthe paper is accomplished as described above, so that said light sourceis only turned on intermittently for a very limited time. Thus, thepremature exposure of the photocopying paper prior to the projection ofan image thereupon for copying can be prevented, so that no pre-exposurepreventive filter is utilized. Furthermore, the long service life ofsaid light source is thus ensured.

The normally-closed switch used by the paper cutting device fordetermining the length of the paper to be cut off is also utilized as anormally-closed switch of the paper feed device control circuit asdescribed above. Therefore, the improved design may be effected withoutincreasing a number of components. Even where the predetermined lengthof photocopying paper is varied, the remaining photocopying paper, if ithas a length less than a predetermined one, will be prevented fromfeeding into the machine, so that the arrangement in accordance with thepresent invention is more advantageous than the arrangement in whichindependent switches are provided.

The above and other objects, features and ad vantages of the presentinvention will become more apparent from the following description ofone illustrative embodiment thereof with reference to the accompanyingdrawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic side view of anembodiment of the present invention; and

FIG. 2 is a circuit diagram thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a roll ofphotocopying paper 1 is loosely carried by a supporting shaft 1a. Theleading end of the roll of paper passes over a guide roller 2 andbetween a pair of feed rollers 3. The pair of feed rollers 3 comprises aroller 3a and a pressure roller 3b which coacts with the roller 3aduring a feeding step. Normally roller 3b is spaced apart from roller 3abut during the feeding operation it is pressed against it by a solenoid3d when a feed switch 3c is closed from the exterior (See FIG. 2 Duringfeeding, the roller 3a is driven soas to advance the photocopying paper.Any other suitable feed means may be employed instead of the above feedrollers 3.

The leading end of the photocopying paper 1 is advanced by the pair offeed rollers 3 toward a cutter device 4, a charger 5, and an exposuredevice 6. The cutter device 4 is comprised of a fixed cutter blade 4aand a movable cutter blade 4b which coacts with the fixed cutter blade4a for cutting off a predetermined length of photocopying paper. Themovable cutter blade 4b is normally spaced away from the path of thephotocopying paper. A normally-closed switch 7 is disposed adjacent tothe end of the photocopying paper path within the exposure device 6 fordetermining the size of the photocopying paper to be cut off. Anactuating member 7a of the switch 7 is caused to move by the leading endof the photocopying paper which thereby opens switch 7. The switch 7 iselectrically connected to the solenoid 4c of the cutter device 4 so thatthe movable cutter blade 4b is caused to coact with the fixed cutterblade 4a when the normally-closed switch 7 is opened, thereby cuttingoff the photocopying paper into a predetermined size. Since, as will beexplained below, the opening of switch 7 also stops feeding by the feedrollers 3, it may be seen that paper feed comes to a halt at the sametime that the cutter device 4 severs a desired length of paper from theroll. It will be understood that any other suitable cutter device may beemployed. The piece of photocopying paper out into a predetermined sizein the manner described above is fed into the exposure device 6 by meansof a suitable conveyor means or the like (not shown) and after exposurethe photocopying paper is further fed into a developing device 8, inwhich the exposed photocopying paper is advanced through the passage P,defined by a pair of upper and lower guide members 8c by two pairs offeed rollers 8a and 8b disposed on both ends of the guide membersrespectively, and is then developed in a manner well known in the art.The rolled photocopying paper 1 is consumed gradually as thephotocopying process is cycled in the manner as described above. Therolled photocopying paper 1 is illuminated by the light from a lightsource 9 and the reflected light is detected by a phototransducerelement 10 such as a photoconductive element. The distance 1 of thepassage P,, from the point of reflection A to the cutter device 4 ismade longer than the length L, of the passage P between, for example,the two pairs of feed rollers 8a and 8b. The light source 9 and thephotoconductive element 10 may be disposed at any position betweenrolled photocopying paper 1 and the pair of feed rollers 3 as long asthe above distance requirement is satisfied.

The quantity of the reflected light incident upon the photoconductiveelement 10 depends upon the presence or absence of rolled photocopyingpaper 1. The output of the photoconductive element 10 variesaccordingly. In accordance with the present invention, the variation inthe output of the photoconductive ele ment 10 is detected by a feedcontrol circuit which will be described in more detail below. The feedcontrol circuit controls the pair of feed rollers 3 so that only whenthe light from light source 9 is reflected from photocopying paper atpoint A will the rollers advance the photocopying paper into the variousprocessing devices described above. Therefore, when the rolledphotocopying paper 1 is almost completely used up, so that a lengththereof I less than 1, is in the passage P, with its leading end in thecutter device 4, there is no photocopying paper at the point A so thatthe feed device 3 is not actuated and no photocopying paper is fed.Operation of the device may be aided by providing a hub for the rolledphotocopying paper of a black color to increase the variation inreflected light when the last of the photocopying paper leaves the hub.

Next the feed device control circuit of the present invention will bedescribed. In addition to falling upon the photocopy paper at point A,light from the light source 9 also passes through a filter 11 which isadapted to dim it and falls upon a fixed photoconductive element 12. Thephotoconductive element 12 serves to compensate or correct forvariations in the resistance of the photoconductive element 10 which maybe caused by temperature variations. As may be seen in FIG. 2, thecopying machine is provided with a main switch 13; a normally-openswitch 14 in a power supply circuit for the feed device 3; and atransformer 15 whose primary is connected to switch 13 through anormally-closed switch 7. A paper feed switch 3c connects the solenoid3d with the normally-open switch 14. Thus, the normally-open switch 14,paper feed switch 30 and the solenoid 3d are connected in parallel withthe switch 7, and the primary of the transformer 15 together with thecircuit containing the solenoid 3d are connected to the main switch 13.

The secondary of the transformer is connected to a paper feed devicecontrol circuit which includes a circuit for the light source 9 and acircuit for the photoconductive elements 10 and 12. A low voltage DCpower supply circuit is comprised of the secondary of the transformer15, a diode 16, a capacitor 17, a resistor l8 and a Zener diode 19. Tothis low voltage DC power supply circuit are connected in series thephotoconductive elements 10 and 12 and transistors 21 and 22 which arecoupled through a Zener diode with each other as shown. The relay 23 foractuating the normally-open switch 14 is controlled by the transistors21 and 22. Reference numeral 24 designates a self-holding normally-openswitch for the relay 23 and reference numeral designates anormally-closed switch operated by the relay 23. The normally-closedswitch 25 is connected to the light source 9. As a variation, thenormally-closed switch 7 may be connected in the power supply circuitfor the relay 23 on the secondary side of the transformer 15.

The operation of the paper feed device control circuit is as follows.When the power switch 13 is first closed DC current is supplied to thephotoconductive elements 10 and 12 through the normally-closed switch 7,the transformer 15, the diode 16, the capacitor 17, the resistor 18, andthe Zener diode 19. At the same time the light source 9 is turned on.When the light from the light source 9 is reflected at the point A bythe photocopy paper 1, the intensity of light incident upon thephotoconductive element 10 is stronger so that the resistance of thephotoconductive element 10 is much less than that of the photoconductiveelement 12. Thus,

because of the voltage division, the base voltage of the transistor 21is higher than the Zener voltage of the Zener diode 20 so that both ofthe transistors 21 and 22 are driven into the conductive state. Currentthrough these transistors activates the relay 23 so that thenormally-open switch 24 is closed, and the relay 23 becomesself-holding. Simultaneously, the normallyclosed switch 25 is opened sothat the light source 9 is turned off and the normally-open contact 14is closed, so that the paper feed device 3 is actuated.

When there is no photocopying paper 1 at the point A, that is, when theremaining photocopying paper 1 is less than a predetermined length, thehub of the roll of photocopying paper is illuminated by the light fromthe light source 9 so that the reflected light is incident upon thephotoconductive element 10. But in this case, the intensity of thereflective light is so weak that the resistance of the photoconductiveelement 10 becomes higher than that of the photoconductive element 12.As a result, the base voltage of the transistor 21 becomes lower thanthat across the Zener diode 20, so that neither of the transistors 21and 22 are conductive. Therefore, the relay 23 is not actuated and thenormally-open switch 14 is opened so that even when the paper feedswitch 3c is depressed, the paper feed device 3 is not actuated at all.The normally-closed switch 7 for the cutter device 4 is temporarilyopened whenever the leading edge of the photocopying paper reaches theswitch 7 as described above, but as soon as the photocopying paper hasleft the switch 7, it is closed again so that the paper feed devicecontrol circuit is also closed. According to the present invention,whenever the paper is fed, a measurement is made of the remainingphotocopying paper to determine whether it is of a sufficient length tobe cut off into a predetermined size. This can also be done when themain switch 13 is closed when the copying machine is started.

When the main switch 13 is closed, current flows through normally-closedswitch 7 and the primary of the transformer 15. Current also flowsthrough the secondary circuit through light source 9 and thenormally-closed switch 25, causing the light source to illuminate pointA. If photocopying paper is present at point A, transistors 21 and 22conduct current from the secondary of the transformer 15 through therelay 23. Activation of relay 23 in this manner closes the normally-openswitch 24 and renders the relay self-holding by establishing analternate current path for current flowing through the relay. Activationof relay 23 opens the normally-closed switch 25 and darkens light source9. Simultaneously, relay 23 closes normally-open switch 14. When feedswitch 30 is closed under these conditions, solenoid 3d moves the pairof feed rollers 3 toward each other and initiates the advance ofphotocopying paper through the machine. This advance continues until theleading edge of the paper opens normally-closed switch 7. Opening ofswitch 7 causes the solenoid 4c of the cutter device 4 to operate thecutter device to cut the photocopy paper. The opening of switch 7 alsobreaks the current flow to the solenoid 23 and results in the opening ofthe normallyopen switch 14, thus deenergizing the paper feed solenoid 3dand halting the advance of photocopy paper from the roll 1. When thesevered segment of the photocopying paper has been advanced fullythrough the charger exposure area and into the developing device, switch7 can again close and initiate the next copying cycle by causing thefeed device control circuit to again ascertain whether or notphotocopying paper remains on the roll 1.

The present invention have been so far described with particularreference to one illustrative embodiment thereof, but it will beunderstood that variations and modifications can be effected withoutdeparting from the true spirit of the present invention as describedabove and as defined in the following claims.

Iclaim:

1. A photocopying paper detecting device for use with copying machineshaving a passage for the feeding of photocopying paper comprisingphotocopying paper supply means including a first point area locatedthereon from which the paper is led therefrom;

drive means for feeding said paper along a feed path for said drivenpaper having a plurality of stations therealong comprising in sequence:

a cutter station,

a charger station,

an exposure station, and

a developing station;

said cutter station defining a second point area along said feed path;

said developing station having third and fourth point areas locatedtherein along said feed path defining a first predetermined lengthwithin which the paper is developed;

said cutter station second point area spaced from said first point areaso that a second predetermined length exists therebetween that isgreater than said first predetermined area;

detecting means located adjacent said first point area, said detectingmeans including a light source for detecting the presence of paper atsaid first point area and thereby generating an electrical signal;

electrical circuit means for said drive means including a firstnormally-closed switch located between said exposure station and saiddeveloping station, said normally-closed switch opened by the passage ofa leading end of paper previously cut at said cutter station whereby thefeed is temporarily interrupted for cutting the paper at said cutterstation;

said circuit means further including:

a first normally-open switch that prevents actuation of said drive meansin its open position,

a second normally-open switch that is closed by application of saidelectrical signal thereby closing said first normally-open switch toactuate said drive means; and

a second normally-closed switch connected in circuit relationship withsaid light source, said second normally-closed switch being opened whensaid second normally-open switch closes to thereby de-actuate said lightsource.

2. A photocopying paper detecting device according to claim 1 in whichsaid circuit means includes activatable means that is electricallyconductive when the paper is present at said first point area, andnon-conductive when the paper is not present at said first point area,and said circuit means further includes an electrical relay that isactuated when said activatable means is conductive to cause closing ofboth said first and second normally-open switches and opening of saidsecond normally-closed switch, said relay becoming self-holding whenconductive.

3. A photocopying paper detecting device according to claim 1 in whichsaid third and fourth point areas are defined by spaced roller meanslocated within said developing station, and the paper positioned betweensaid roller means having a length at least as long as said secondpredetermined distance.

1. A photocopying paper detecting device for use with copying machineshaving a passage for the feeding of photocopying paper comprisingphotocopying paper supply means including a first point area locatedthereon from which the paper is led therefrom; drive means for feedingsaid paper along a feed path for said driven paper having a plurality ofstations therealong comprising in sequence: a cutter station, a chargerstation, an exposure station, and a developing station; said cutterstation defining a second point area along said feed path; saiddeveloping station having third and fourth point areas located thereinalong said feed path defining a first predetermined length within whichthe paper is developed; said cutter station second point area spacedfrom said first point area so that a second predetermined length existstherebetween that is greater than said first predetermined area;detecting means located adjacent said first point area, said detectingmeans including a light source for detecting the presence of paper atsaid first point area and thereby generating an electrical signal;electrical circuit means for said drive means including a firstnormally-closed switch located between said exposure station and saiddeveloping station, said normally-closed switch opened by the passage ofa leading end of paper previously cut at said cutter station whereby thefeed is temporarily interrupted for cutting the paper at said cutterstation; said circuit means further including: a first normally-openswitch that prevents actuation of said drive means in its open position,a second normally-open switch that is closed by application of saidelectrical signal thereby closing said first normallyopen switch toactuate said drive means; and a second normally-closed switch connectedin circuit relationship with said light source, said secondnormallyclosed switch being opened when said second normally-open switchcloses to thereby de-actuate said light source.
 2. A photocopying paperdetecting device according to claim 1 in which said circuit meansincludes activatable means that is electrically conductive when thepaper is present at said first point area, and non-conductive when thepaper is not present at said first point area, and said circuit meansfurther includes an electrical relay that is actuated when saidactivatable means is conductive to cause closing of both said first andsecond normally-open switches and opening of said second normally-closedswitch, said relay becoming self-holding when conductive.
 3. Aphotocopying paper detecting device according to claim 1 in which saidthird and fourth point areas are defined by spaced roller means locatedwithin said developing station, and the paper positioned between saidroller means having a length at least as long as said secondpredetermined distance.